1. Technical Field
This application relates to mobile telecommunications systems in general, having particular application in UMTS (Universal Mobile Telecommunications System) in general, and in particular relates to an apparatus and method for power measurement summation in mobile telecommunications system user equipment.
2. Description of the Related Art
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In a typical cellular radio system, mobile user equipment (UE) communicates via a radio access radio network (RAN) to one or more core networks. User equipment (UE) comprises various types of equipment such as mobile telephones (also known as cellular or cell phones), lap tops with wireless communication capability, personal digital assistants (PDAs) etc. These may be portable, hand held, pocket sized, installed in a vehicle etc and communicate voice and/or data signals with the radio access network.
In the following, reference will be made to UMTS and to particular standards. However it should be understood that the invention is not intended to be limited to any particular mobile telecommunications system.
The radio access network covers a geographical area divided into a plurality of cell areas. Each cell area is served by at least one base station, which in UMTS may be referred to as a Node B. Each cell is identified by a unique identifier which is broadcast in the cell. The base stations communicate at radio frequencies over an air interface with the UEs within range of the base station. Several base stations may be connected to a radio network controller (RNC) which controls various activities of the base stations. The radio network controllers are typically connected to a core network.
UMTS is a third generation public land mobile telecommunication system. Various standardization bodies are known to publish and set standards for UMTS, each in their respective areas of competence. For instance, the 3GPP (Third Generation Partnership Project) has been known to publish and set standards for GSM (Global System for Mobile Communications) based UMTS, and the 3GPP2 (Third Generation Partnership Project 2) has been known to publish and set standards for CDMA (Code Division Multiple Access) based UMTS. Within the scope of a particular standardization body, specific partners publish and set standards in their respective areas.
Consider a wireless mobile device, generally referred to as user equipment (UE), that complies with the 3GPP specifications for the UMTS protocol. The 3GPP 25.331 specification, v.3.15.0, referred to herein as the 25.331 specification, addresses the subject of UMTS RRC (Radio Resource Control) protocol requirements between the UMTS Terrestrial Radio Access Network (UTRAN) and the UE.
Power may be measured on a linear scale (e.g. Watts) or on a logarithmic scale (e.g. decibels (dB)). There are many instances of power measurements in 3G and some of these include summing power measurements from a number of cells to determine operating conditions of the network and/or the user equipment. For instance, among others, clauses 14.1.2.1 and 14.1.2.2 of the 25.331 specification relate to intra-frequency reporting events for FDD (Frequency Division Duplex) systems and set out the conditions for determining whether the user equipment is to trigger the start of an event. For instance, the UE determines whether there is a triggering condition for pathloss by calculating the following:
                    10        ·        Log            ⁢                          ⁢              M        New              +          CIO      New        ≤            W      ·      10      ·              Log        ⁡                  (                      1            /                                          ∑                                  i                  =                  1                                                  N                  A                                            ⁢                              (                                  1                  /                                      M                    i                                                  )                                              )                      +                            (                      1            -            W                    )                ·        10        ·        Log            ⁢                          ⁢              M        Best              +          (                        R                      1            ⁢            a                          -                              H                          1              ⁢              a                                /          2                    )      where, in particular, M represents power measurements in Watts i.e. on a linear scale. However power measurements are in many cases received in decibels i.e. on a logarithmic scale. To sum these for the purposes of equations such as those shown above, it would therefore be necessary to convert these measurements to the linear scale, sum the measurements and then use a log function to convert the result back to the logarithmic scale.
The maths processor needed by a device to carry out such a conversion may be unjustified given other processing demands of a device. There is thus a need to calculate a sum of power measurements without having to carry out these conversions. There are thus proposed strategies for power measurement summation in mobile telecommunications system user equipment. A number of such strategies are detailed below.
Other aspects and features of the proposed strategies will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of an apparatus and method for power measurement summation in mobile telecommunications system user equipment.
The same reference numerals are used in different figures to denote similar elements.